/*
 * Copyright � 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using Spring.Expressions;
using Spring.Util;

namespace Spring.Validation;

/// <summary>
/// Validates that required value is not empty.
/// </summary>
/// <remarks>
/// <p>
/// This validator uses following rules to determine if target value is valid:
/// <table>
///     <tr>
///         <th>Target <see cref="System.Type"/></th>
///         <th>Valid Value</th>
///     </tr>
///     <tr>
///         <td>A <see cref="System.String"/>.</td>
///         <td>Not <see lang="null"/> or an empty string.</td>
///     </tr>
///     <tr>
///         <td>A <see cref="System.DateTime"/>.</td>
///         <td>Not <see cref="System.DateTime.MinValue"/> and not <see cref="System.DateTime.MaxValue"/>.</td>
///     </tr>
///     <tr>
///         <td>One of the number types.</td>
///         <td>Not zero.</td>
///     </tr>
///     <tr>
///         <td>A <see cref="System.Char"/>.</td>
///         <td>Not <see cref="System.Char.MinValue"/> or whitespace.</td>
///     </tr>
///     <tr>
///         <td>Any reference type other than <see cref="System.String"/>.</td>
///         <td>Not <see lang="null"/>.</td>
///     </tr>
/// </table>
/// </p>
/// <p>
/// You cannot use this validator to validate any value types other than the ones
/// specified in the table above.
/// </p>
/// </remarks>
/// <author>Aleksandar Seovic</author>
public class RequiredValidator : BaseSimpleValidator
{
    /// <summary>
    /// Creates a new instance of the <see cref="RequiredValidator"/> class.
    /// </summary>
    public RequiredValidator()
    {
    }

    /// <summary>
    /// Creates a new instance of the <see cref="RequiredValidator"/> class.
    /// </summary>
    /// <param name="test">The expression to validate.</param>
    /// <param name="when">The expression that determines if this validator should be evaluated.</param>
    public RequiredValidator(string test, string when) : base(test, when)
    {
        AssertUtils.ArgumentHasText(test, "test");
    }

    /// <summary>
    /// Creates a new instance of the <see cref="RequiredValidator"/> class.
    /// </summary>
    /// <param name="test">The expression to validate.</param>
    /// <param name="when">The expression that determines if this validator should be evaluated.</param>
    public RequiredValidator(IExpression test, IExpression when) : base(test, when)
    {
        AssertUtils.ArgumentNotNull(test, "test");
    }

    /// <summary>
    /// Validates the supplied <paramref name="objectToValidate"/>.
    /// </summary>
    /// <remarks>
    /// In the case of the <see cref="Spring.Validation.RequiredValidator"/> class,
    /// the test should be a variable expression that will be evaluated and the object
    /// obtained as a result of this evaluation will be tested using the rules described
    /// in the class overview of the <see cref="Spring.Validation.RequiredValidator"/>
    /// class.
    /// </remarks>
    /// <param name="objectToValidate">The object to validate.</param>
    /// <returns>
    /// <see lang="true"/> if the supplied <paramref name="objectToValidate"/> is valid.
    /// </returns>
    protected override bool Validate(object objectToValidate)
    {
        if (objectToValidate is String && StringUtils.IsNullOrEmpty((string) objectToValidate))
        {
            return false;
        }
        else if (objectToValidate is DateTime && (((DateTime) objectToValidate) == DateTime.MinValue || ((DateTime) objectToValidate) == DateTime.MaxValue))
        {
            return false;
        }
        else if (NumberUtils.IsInteger(objectToValidate) && NumberUtils.IsZero(objectToValidate))
        {
            return false;
        }
        else if (objectToValidate is Char && (((char) objectToValidate) == Char.MinValue || Char.IsWhiteSpace((char) objectToValidate)))
        {
            return false;
        }
        else if (NumberUtils.IsDecimal(objectToValidate) && NumberUtils.IsZero(objectToValidate))
        {
            return false;
        }

        return objectToValidate != null;
    }
}
